1. Field of the Invention
This invention relates to sheet roofing systems.
2. Description of Prior Art
Traditionally many roofs, especially roofs of large buildings such as arenas, barns, industrial warehouses and the like, have been made from sheet metal material. Sheet metals tend to be expensive and are difficult to handle, especially in high winds. Joins between the sheets have needed special waterproofing techniques. When the metal sheets are intended to be especially decorative rather than merely utilitarian, the expense is even greater. Frequently such decorative metal sheets may be formed of copper.
While metal roofing systems have not been superseded it has become relatively common to use, in their place or to cover them, roofing systems in which the covering material is a flexible plastics material. Frequently the plastics material is ethylene propylene diene monomer (EPDM rubber). Alternatively it may be polyvinyl chloride (PVC). Either of these materials may be coloured either to mimic the colourings of natural metal roofing systems or in other colours that can only be achieved on metal by paint or other coating.
In one respect, metal sheeting may have some small advantage over the conventional use of plastic sheet in that metal sheeting may be provided with molded decorative ribs and grooves or other decorations. This type of decoration cannot conveniently be molded into flexible plastic sheeting in the same way as is possible for semi-rigid or rigid metal sheet. Metal sheeting is usually joined one sheet to another at an upstanding crimped seam, which may be made as a decorative feature.
If the metal sheet is to be covered with plastic sheet it may be convenient to join adjacent plastic sheets at the crimped join so that the join in the plastic sheet may be incorporated in the decorative appearance of the join. Alternatively, the plastics sheet may cover the crimped seam.
The geometry of a crimped seam can vary generally from 1 inch to 31/4 inches high although other heights are possible. Usually the seam has a bulge to one side due to the bent over crimp.
Sometimes plastics material sheet such as PVC sheet is applied over an existing metal roof which is often a sloping roof. Whether or not, the body of the plastics sheet or overlapping edges of adjacent plastics sheets coincide with a standing seam, difficulties arise in providing a neat fit of the plastics sheet with the roof contour at this point in water. When overlapping edges occur, waterproofing may be a problem.
U.S. Pat. No. 4,833,853 to Deibele et al discloses mechanical fixing system at the edges of plastic sheet in which an elongated mounting bracket provides a grip for a cover member. The plastic sheet is attached to the mounting bracket by screws and the cover member provides waterproofing. The mounting bracket is of complex form and the edges of overlapping sheets are drawn up to cover the head of the screw. There is, however, no provision for the presence of a standing seam.
Exemplary of patents concerning semi-rigid or rigid roofing sheets is U.S. Pat. No. 4,366,656 issued Jan. 4, 1983 to Simpson. U.S. Pat. No. 4,269,012 issued May 26, 1981 to Mattingly et al discloses a roofing system in which the edge of one metal sheet is bent to form a cover for the edge of an adjacent sheet. In the disclosure of this patent, a cap is shown over the standing seam to prevent water ingress. No covering plastics sheet is used.
The present inventor has addressed the problem of laying a cover plastics sheet material over a standing seam of a metal roof or indeed over any upstanding ridge. Since many colours are available in plastics sheet, it is desirable that any waterproofing or fixing of the sheet in the region of the standing seams or other ridges should match or provide other decorative finish with respect to the sheet colour. The present inventor has also addressed the problem of providing simplicity of installation with a minimum number of parts; and the need to keep the installation inexpensive by minimizing labour costs.